New types of devices equipped with specific application execution environments are being provided in recent years even in the field of mobile communication devices like mobile phones and PHS's. For example, for a mobile phone equipped with a Java® execution environment, the application developer designs a Java application program by use of various class library groups, etc. which are configured on the Java virtual machine. Incidentally, a standard called “MIDP” (Mobile Information Device Profile) has been proposed as one of such Java environments provided for mobile phones, and an application configured on MIDP is sometimes called a “MIDlet”.
In Japanese Patent Provisional Publication No. 2003-169372, a configuration for modifying an application operating on a mobile phone into a call-notifying type has been described. An application of the call-notifying type is controlled to display information indicating an incoming call on the display screen when there is an incoming call during the execution of the application. In the publication, it is described that interruption of the application due to an incoming call, etc. can be prevented by such control.